Master's thesis The Signal Processing in ZigBee System is focused on properties of Physical Layer of ZigBee (standard IEEE 802.15.4 - 2003). The work consists of three parts. The first part contains common view on using and properties of ZigBee. The next part focuses on the Medium Access Control Layer and in detail on the Physical Layer. There described signal processing in the Physical Layer in individual radio bands. The last part of the project contains the process of modeling in the MATLAB for both models of system ZigBee (bands 868/915 MHz and 2450 MHz). The last part of thesis deals with the simulations of BER depending on Carrier-to-Noise Ratio. Also examined the coexistence of systems operating in the same or a nearby frequency band. Based on the results of simulations there are given recommendations for the use of the ZigBee system in minimizing BER.

<p>Background: Many systems that Enea Epact AB develops for theirs customers communicates with computers. In order to meet the customers demands on cost effective solutions, Enea Epact wants to know if it is possible to implement a gigabit Ethernet controller in an FPGA. The controller shall be designed with the intent to meet the requirements of IEEE 802.3. </p><p>Aim: Find out if it is feasible to implement a gigabit Ethernet controller using an FPGA. In the meaning of feasible, certain constraints for size, speed and device must be met. </p><p>Method: Get an insight of the standard IEEE 802.3 and make a rough design of a gigabit Ethernet controller in order to identify parts in the standard that might cause problem when implemented in an FPGA. Implement the selected parts and evaluate the results. </p><p>Conclusion: It is possible to implement a gigabit Ethernet controller using an FPGA and the FPGA does not have to be a state-of-the-art device.</p>

Background: Many systems that Enea Epact AB develops for theirs customers communicates with computers. In order to meet the customers demands on cost effective solutions, Enea Epact wants to know if it is possible to implement a gigabit Ethernet controller in an FPGA. The controller shall be designed with the intent to meet the requirements of IEEE 802.3. Aim: Find out if it is feasible to implement a gigabit Ethernet controller using an FPGA. In the meaning of feasible, certain constraints for size, speed and device must be met. Method: Get an insight of the standard IEEE 802.3 and make a rough design of a gigabit Ethernet controller in order to identify parts in the standard that might cause problem when implemented in an FPGA. Implement the selected parts and evaluate the results. Conclusion: It is possible to implement a gigabit Ethernet controller using an FPGA and the FPGA does not have to be a state-of-the-art device.

Dans les systèmes de communications sans fil, la transmission de grandes quantités d'information et à faible coût énergétique sont les deux principales questions qui n'ont jamais cessé d'attirer l'attention de la communauté scientifique au cours de la dernière décennie. Récemment, il a été démontré que la communication coopérative est une technique intéressante notamment parce qu'elle permet d'exploiter la diversité spatiale dans le canal sans fil. Cette technique assure une communication robuste et fiable, une meilleure qualité de service (QoS) et rend le concept de coopération prometteur pour les futurs générations de systèmes cellulaires. Typiquement, les QoS sont le taux d'erreurs paquet, le débit et le délai. Ces métriques sont impactées par le délai, induit par les mécanismes de retransmission Hybrid-Automatic Repeat-Request (HARQ) inhérents à la réception d'un paquet erroné et qui a un retard sur la QoS demandée. En revanche, les mécanismes HARQ créent une diversité temporelle. Par conséquent, l'adoption conjointe de la communication coopérative et des protocoles HARQ pourrait s'avérer avantageux pour la conception de schémas cross-layer. Nous proposons tout d'abord une stratégie de maximisation de débit total dans un réseau cellulaire hétérogène. Nous introduisons un algorithme qui alloue la puissance optimale à la station de base (BS) et aux relais, qui à chaque utilisateur attribue de manière optimale les sous-porteuses et les relais. Nous calculons le débit maximal atteignable ainsi que le taux d'utilisateurs sans ressources dans le réseau lorsque le nombre d'utilisateurs actifs varie. Nous comparons les performances de notre algorithme à ceux de la littérature existante, et montrons qu'un gain significatif est atteint sur la capacité globale. Dans un second temps, nous analysons théoriquement le taux d'erreurs paquet, le délai ainsi que l'efficacité de débit des réseaux HARQ coopératifs, dans le canal à évanouissements par blocs. Dans le cas des canaux à évanouissement lents, le délai moyen du mécanisme HARQ n'est pas pertinent à cause de la non-ergodicité du processus. Ainsi, nous nous intéressons plutôt à la probabilité de coupure de délai en présence d'évanouissements lents. La probabilité de coupure de délai est de première importance pour les applications sensibles au délai. Nous proposons une forme analytique de la probabilité de coupure permettant de se passer de longues simulations. Dans la suite de notre travail, nous analysons théoriquement l'efficacité énergétique (bits/joule) dans les réseaux HARQ coopératifs. Nous résolvons ensuite un problème de minimisation de l'énergie dans les réseaux coopératifs en liaison descendante. Dans ce problème, chaque utilisateur possède une contrainte de délai moyen à satisfaire de telle sorte que la contrainte sur la puissance totale du système soit respectée. L'algorithme de minimisation permet d'attribuer à chaque utilisateur la station-relai optimale et sa puissance ainsi que la puissance optimale de la BS afin de satisfaire les contraintes de délai. Les simulations montrent qu'en termes de consommation d'énergie, les techniques assistées par relais prédominent nettement les transmissions directes, dans tout système limité en délai. En conclusion, les travaux proposés dans cette thèse peuvent promettre d'établir des règles fiables pour l'ingénierie et la conception des futures générations de systèmes cellulaires énergétiquement efficaces. / In wireless systems, transmitting large amounts of information with low energetic cost are two main issues that have never stopped drawing the attention of the scientific community during the past decade. Later, it has been shown that cooperative communication is an appealing technique that exploits spatial diversity in wireless channel. Therefore, this technique certainly promises a robust and reliable communications, higher quality-of-service (QoS) and makes the cooperation concept attractive for future cellular systems. Typically, the QoS requirements are the packet error rate, throughput and delay. These metrics are affected by the delay, where each erroneous packet is retransmitted several times according to Hybrid-Automatic Repeat-Request (HARQ) mechanism inducing a delay on the demanded QoS but a temporal diversity is created. Therefore, adopting jointly cooperative communications and HARQ mechanisms could be beneficial for designing cross-layer schemes. First, a new rate maximization strategy, under heterogeneous data rate constraints among users is proposed. We propose an algorithm that allocates the optimal power at the base station (BS) and relays, assigns subcarriers and selects relays. The achievable data rate is investigated as well as the average starvation rate in the network when the load, i.e. the number of active users in the network, is increasing. It showed a significant gain in terms of global capacity compared to literature. Second, in block fading channel, theoretical analyses of the packet error rate, delay and throughput efficiency in relayassisted HARQ networks are provided. In slow fading channels, the average delay of HARQ mechanisms w.r.t. the fading states is not relevant due to the non-ergodic process of the fading channel. The delay outage is hence invoked to deal with the slow fading channel and is defined as the probability that the average delay w.r.t. AWGN channel exceeds a predefined threshold. This criterion has never been studied in literature, although being of importance for delay sensitive applications in slow fading channels. Then, an analytical form of the delay outage probability is proposed which might be useful to avoid lengthy simulations. These analyses consider a finite packet length and a given modulation and coding scheme (MCS) which leads to study the performance of practical systems. Third, a theoretical analysis of the energy efficiency (bits/joule) in relay-assisted HARQ networks is provided. Based on this analysis, an energy minimization problem in multiuser relayassisted downlink cellular networks is investigated. Each user has an average delay constraint to be satisfied such that a total power constraint in the system is respected. The BS is assumed to have only knowledge about the average channel statistics but no instantaneous channel state information (CSI). Finally, an algorithm that jointly allocates the optimal power at BS, the relay stations and selects the optimal relay in order to satisfy the delay constrains of users is proposed. The simulations show the improvement in terms of energy consumption of relay-assisted techniques compared to nonaided transmission in delay-constrained systems. Hence, the work proposed in this thesis can give useful insights for engineering rules in the design of the next generation energyefficient cellular systems.

The diploma thesis is focused on the building embedded demonstration application of the proprietary Low Complexity Ethernet module for industrial usage further called the LEN/LES 2. At the first, main used technologies such as MCU, or the lightweight IP stack is discussed, Consequently, there is detailed view on system hardware architecture proposed by hardware and software requirements. Then though part describes blocks of embedded system are in term of specific parts and hardware requirements to create universal board. Following chapters expresses first startup and known hardware bugs, LWIP implementation and MODBUS system implementation. The core of the system is the new released microcontroller an ADuCM4050 and the Low Complexity Ethernet MAC-PHY prototype block and much more dependent convenient peripherals of the MCU based application.

This master’s thesis deals with the design of six channel SD, HD and 3G HD-SDI digital video signal converter to 10-Gigabit Ethernet. In the introductory part, the conception of designed device is formulated. The theoretical background is provided in four chapters, where main standards and design rules related to digital electronics’ design are analyzed. The emphasis is placed on signal integrity at high-speed interconnects. There mostly practical examples, calculations and simulations are utilized. The design part contains thorough description of main subsystems’ design, implementation of FPGA, SDI input channels and 10-Gigabit Ethernet PHY. In the final part, the first tests and measurements of the build prototype are summarized. As an example, the comparison of signal integrity simulation to measurement is provided.

No description available.

Cette thèse a pour objectif l¤étude des mécanismes d¤interaction inter-couche et leurs applications pour des algorithmes adaptatifs pour contrôler les paramètres de transmission. Après une description rapide des protocoles des couches liaison et physiques du standard IEEE 802.11, nous présentons une analyse de performance des modes de transmission spécifiés par les normes 802.11a/b. La deuxième contribution de cette thèse porte sur la modélisation des réseaux 802.11. Nous proposons un modèle analytique qui prend en compte la position des terminaux radio par rapport au point d¤accès afin d¤évaluer les performances de la couche MAC. Nous proposons ensuite de nouveaux mécanismes de sélection du débit de transmission physique. Nous avons élaboré l¤algorithme AARF, basé sur l¤algorithme ARF, qui s'intéresse à la classe des terminaux dits à faible latence et offre des services d¤adaptation à court et à long terme. Un autre algorithme basé sur les mêmes idées que celles développées pour AARF, mais conçu pour fonctionner avec des systèmes à grande latence, a été implanté et expérimenté sur des terminaux à base du processeur Atheros. Enfin, nous avons élaboré un troisième algorithme de contrôle dynamique du mode de transmission en boucle fermée appelé CLARA qui est compatible avec les standards 802.11a/b/g. La dernière contribution de cette thèse porte sur l¤optimisation de la transmission de flots multimédias temps réel sur des réseaux 802.11. Nous présentons MORSA, un mécanisme d¤optimisation inter-couche efficace qui permet de sélectionner le mode de transmission à utiliser en fonction de l'état du canal de transmission et des caractéristiques de l'application.

<p>There are several standards for wireless communication. People that are involved in computers and networking recognize names like Bluetooth, HiperLAN and IEEE 802.11. The last one was standardized in 1997 [2,6]and has begun to reach acceptance as a solid ground for wireless networking. A fundamental part of an IEEE 802.11 node is the Medium Access Controller, or MAC. It establishes and controls communication with other nodes, using a physical layer unit. </p><p>The work has been carried out as final project at Linkopings Universitet, it has been about the improvement of the functions of MAC layer. I have developed some of the required functions that PUM uses to interact with the MAC layer. Because of that, I have implemented the Reception functions of MAC layer, having the possibility of using short control frames RTS/CTS to minimize collision.</p>

<p>With the 1999 introduction of IEEE 802.11b, the 2.4 GHz Wireless Local Area Network (WLAN) standard, the WLAN market finally began to experience the growth levels that had been expected for so long. Now, 5 GHz solutions, with the IEEE 802.11a standard leading the way, offer higher throughput and more efficient use of the spectrum. Just as the 2.4 GHz band, the 5 GHz band is unlicensed. A common concern to all unlicensed bands is interference between devices using the spectrum. Furthermore, in the 5 GHz band, WLAN cells can interfere with radar systems operating at the same frequencies. </p><p>This report describes a software model, WOK, suitable for simulations of IEEE 802.11a WLANs operating in various environments and under various ambient conditions. The WOK model can be configured extensively with respect to topology, traffic behavior, channel models, signal attenuation, interference sources and radar systems. </p><p>Further, the concepts of Dynamic Frequency Selection (DFS) and link adaptation are explored in the context of the IEEE 802.11a standard. DFS aims to avoid channels occupied by radar systems and link adaptation aims to maximize the throughput based on current ambient conditions. A DFS algorithm and a link adaptation algorithm are implemented at the Medium Access Control (MAC) layer and evaluated using the WOK model.</p>